1973 340, want more power.

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I think we are getting off track here.

Before you start throwing parts/money at a problem that doesn't exist. LEARN about your car. You don't even know what camshaft or rear gears you got. Basics. I know exactly how many miles my cam has on it. How many times the oil has been changed. I know my rear gears and how many miles are on them. I can probably even tell you how many fart's I've drilled into the seat.

KNOW everything about your car. Then you can know what to change. Can't know what's mismatched until you know whats in there. Otherwise it's like trying to bake a cake blindfolded and without the recipe.
 
MOPEkidD-3 said:
Correct me if I'm wrong but wouldn't a set of RPM heads after being gone through and assembled with good parts be like $2000?
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You can spend that kind of money on RPM's if you like, but I'd buy them from Autozone on sale and save 20% or more so that puts you at around $1350 for pair loaded (+ your sales tax if Autozone has a store in your state), then $100 or so to check them out for any burs in guides, etc. I am not sure what you mean by 'assembled with good parts'.... this price is loaded & assembled with valves, springs, retainers & keepers.

The RPM's breathe over 400 HP easy right out of the box. And there is potential for more of course. Sure is easy HP.....
 
Lustle said:
Before you start throwing parts/money at a problem that doesn't exist. LEARN about your car. You don't even know what camshaft or rear gears you got. Basics. I know exactly how many miles my cam has on it. How many times the oil has been changed. I know my rear gears and how many miles are on them. I can probably even tell you how many fart's I've drilled into the seat.

KNOW everything about your car. Then you can know what to change. Can't know what's mismatched until you know whats in there. Otherwise it's like trying to bake a cake blindfolded and without the recipe.
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Just to play devil's advocate...... If you haven't owned a car for a long time, and you don't have a lot mechanical skills, then IMHO it is too tall of an order to become all that familiar with your car before doing any mods. You might be years before doing anything.

To the point made earlier, about gears, the OP says he likes the present rear gears for cruising. So, my view would be to work with that as a starting point, and not insist that he change them to any particular numerical ratio. It may not be optimum on the strip, but I read the OP as being very happy with a decent high performance car. He should correct me if I am off-base there (please do so!).

BTW, OP to check your rear gear ratio:
1. Jack up the car's rear axle (place jack stands under it) and take it out of gear. Turn one rear wheel while watching the other; if the other turns in the opposite direction, you have an 'open' rear gear carrier (not a limited slip type). If the other wheel turns in the same direction, then you do have a limited slip rear diff (SureGrip for a Mopar).
2. For a limited slip rear axle, place a mark on the driveshaft and turn one wheel exactly 1 turn while watching the driveshaft mark. See exactly how many turns the driveshaft makes when turning the wheel exactly once. For a limited slip type, the number of turns on the driveshaft equals the gear ratio.
3. For an open rear axle, you need to block the other wheel so it does not turn. Then rotate the wheel near to you exactly two turns, and count the number of driveshaft rotations. That will be your rear gear ratio.

Do this as precisely as you can. You should get a number like 3.23, 3.55 or 3.91, etc. Here is an article on this procedure: What Gear Ratio is My Rearend?
 
nm9stheham said:
Just to play devil's advocate...... If you haven't owned a car for a long time, and you don't have a lot mechanical skills, then IMHO it is too tall of an order to become all that familiar with your car before doing any mods. You might be years before doing anything.
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You're absolutely right, it might be years. But that's better than years of chasing a gremlin that doesn't exist, throwing money at something that doesn't need it. OP wants a 12 second street car. Not a really tall order these days. And his car might have it in it already, just needs a few low dollar tweeks. He might love his gears, but maybe that's what's holding him back. Or converter. Or cam. Can't know until we know what's in there. And if he want's 12 seconds, he might have to give up those gears he loves so much. In the end, he has to pick and choose what he wants. Sacrificing those gears so he can reach his mid-low 12's goal. But it can be hard to choose when you aren't sure what you're working with.

I just hate to see guys follow the old "well you need heads" "oh i ran this cam and it was great" "I'd change that carb" advice, when in the end it's all about how the entire combo works together. There is no magic key or magic part, that will suddenly help you hit your goal.
 
I took it from the starting point of "From scratch."
I have noted there are more than a dozen ways to go fast. What ever ya like, do.
 
Some folks just want a parts list... like in the hot rod magazines LOL. Not the way you or I would do it, but hey, different abilities and methods don't change the desire to reach the same end goal. I know I did my first engine 40+ year back from a lot of reading of the hot rod mags and the few books that were out there. I did not understand it all, nor do the optimum, but I sure was thrilled with the results and got a decently good combo (not a strip killer but a good all around performer on the street and highway).

Probably the one thing that helped was doing enough reading to at least compare and contrast and grasp the basics of what did what: cam sizes, breathing, compression, 'effective CR' (i.e. DCR), etc . Not everyone wants to do that..... that is just the way it is. When you are new to the game, lot's o' learning is a good step but even with some dedication, some basics is all most folks can handle in one throw; the curve to real knowledge is pretty steep and those who have it easily forget how far they have come.

Let's give credit to the OP for coming onboard and asking, and try to move things along. At least, he didn't just go out and order the whole Summit catalog LOL. I wonder if he is still listening... things DO get a bit off track from time to time.

Back to the most important questions: What is really wanted?
A true 12 second strip car (and is that 12.00 sec or 12.99 sec? It's a large difference....), or good highway cruiser with some decent punch? As pointed out, the best recommendations all flow from these answers.

Would it be fair to assume this is a stock 340?
 
Helps her breath Richard, less restrictive which always helps performance. Not the seat of the pants feeling type of improvement (IMO), but does improve the sound, at least I like it. Making the scoops functional will route that cool outside air into the carb, and does help performance.

Pat

P.S. Don't we all want more power? LOL!
 
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Rear wheel dyno results were 266.37 hp at 5900 rpm but was at 250 hp from 4600 to5400 rpm. And only 205 hp at 4000 rpm.
Max torque was 276.36 from 4200 rpm to 4700 rpm then started dropping off after that. At 3500 rpm it was only 245. My tires are BFG radial TA's. Not even soft street tires. The line for HP on the chart is like a squiggly line from 5200 to 5800 rpm. One reason I thought the cam might be the issue off the line is because Lunati states it needs at least a 4.10 gear and a 3500 rpm stall. My 3.91 with the 28 in. tall tires is no where close to what the say it needs, and my stall is a little under a 1000rpm less.
Even with the manifolds I thought it should be good for low 13's at around 103mph or so.
 
From what I have read in the thread the OP wants a street friendly car that will push him back in the seat and run in the 12's occasionally at the track, isn't that what most want......staying with his 340 an 8.0CR motor thats (if its in good shape) around 240hp in a car that weighs around 3300+? is at best a 14.0 sec car with it tuned good and not spinning itself to death on the leave. To get in the 12.9's is going to need around 300hp, mid 12's approx 345hp.

One way forward I can see is if your going to keep the bottom end together (8:1), is it will need some good heads, IMM iron or Eddies, something that will flow well at .450>.480" around 250cfm, (thats where its all at), top that off with an rpm intake, hdrs, at least a 750>800 carb to feed the heads, a good tune and high 12's are possible, it can be done on low CR. 3.91's with a tight 2500>2800 stall and some sticky's out back, good rear springs/shocks and perhaps an adjustable snubber with 1" gap to floor (which most will say is old tech) but it still works!. That of course is 1 way, you could simply drop in a 375hp crate motor at $4700 or similar. from summit, as has been suggested....job done.
 
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A well done create engine is a beautiful thing! Contact MRL for that. He has some gems.
 
Thanks a lot guys. I have a lead on a few people that can have a look at my car and tell me exactly what I already have.

What should I ask them to look for? Gears, cam type, head etc???
 
- Rear gears would be fairly easy for anyone who knew their stuff.
- Read the casting numbers off of the heads (under the valve covers) and off the side of the block and from the intake manifold, and the serial number from the pad on the block to see if the numbers all hang together as being a complete, original engine. If so, at least one can then make a decent guess at what is inside there. (You can do all of this part yourself BTW.)
- Transmission type (904 or 727)
- Pull the protection plate off the lower end of the bell housing and look inside to see if the torque converter looks stock or is an obvious replacement
- Carb model number (the 'list number' since that is a Holley that you show)
- Ignition system type (OEM Mopar electronic or what?)
- Any obvious external engine mods like headers, intake, carb, and distributor. If these are there, get as good info on these parts as is possible. Take clear pix too.
- Take compression readings carefully on all 8 cylinders and list them here. As well as your altitude. This may or may not be useful, but at least you will know if the cylinder pressures are fairly even; if not, then more work is indicated.
- If the engine appears to be non-original (with non-original head castings for example), then it is almost a pure wild guess as to what is inside.
 
nm9stheham said:
- Rear gears would be fairly easy for anyone who knew their stuff.
- Read the casting numbers off of the heads (under the valve covers) and off the side of the block and from the intake manifold, and the serial number from the pad on the block to see if the numbers all hang together as being a complete, original engine. If so, at least one can then make a decent guess at what is inside there. (You can do all of this part yourself BTW.)
- Transmission type (904 or 727)
- Pull the protection plate off the lower end of the bell housing and look inside to see if the torque converter looks stock or is an obvious replacement
- Carb model number (the 'list number' since that is a Holley that you show)
- Ignition system type (OEM Mopar electronic or what?)
- Any obvious external engine mods like headers, intake, carb, and distributor. If these are there, get as good info on these parts as is possible. Take clear pix too.
- Take compression readings carefully on all 8 cylinders and list them here. As well as your altitude. This may or may not be useful, but at least you will know if the cylinder pressures are fairly even; if not, then more work is indicated.
- If the engine appears to be non-original (with non-original head castings for example), then it is almost a pure wild guess as to what is inside.
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How do I identify the transmission type?
 
First pic
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Ether is fine. The 904 is lighter and uses less power. Most of the 904's are built with less HD type of internals than a 727, but that doesn't mean there not tuff or can not perform or be made superior. Most high performance minded guys will opt. for the 904 because of the above plus points. There about a 10th quicker in the 1/4 mile. This turns out to be a significant amount of power.
The 727 & 904 can handle and be made to handle a REAL good bit of power.
 
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